1. Field of the Invention
The invention relates to a device for applying a coating medium to at least one partial surface of an elongated workpiece in a vacuum chamber, said device consisting of a housing with a reservoir having an oblique bottom and of an air line issuing into said reservoir and also of a separation means located above the reservoir.
2. Description of the Related Art
It is known to provide elongated workpieces, transported in their longitudinal direction, with a coating medium at least on part of their surface. In this case, the workpieces often consist of wood or wood-containing materials. The coating media used are pumpable and filterable nozzle-compatible liquids, such as pigment solutions, dyes, lacquers and priming and impregnating agents. This coating medium is located in a reservoir which is mostly formed in the lower region of a housing and has an oblique bottom. The coating medium is conveyed from this reservoir to an application unit which is designed as a spraying or flooding frame or as a slit nozzle, depending on the profile or independently of the profile. This application unit is formed in what is known as a vacuum chamber which is connected to a vacuum tank. A stream of finely atomized coating medium and air is formed in this vacuum chamber, the air being sucked in from outside via narrow gaps surrounding the workpiece. The workpiece to be coated is then fed through this stream of finely atomized coating medium and air. In this case, on the one hand, what is known as interstitial air is extracted from the workpiece and, on the other hand, the coating medium settles intensively on the intended surfaces of the workpiece. Excess coating medium is sucked away from the vacuum chamber together with the air and is returned into the housing having the reservoir. Through an orifice located above the reservoir, the air stream laden with excess coating medium enters the housing and impinges there onto a baffle plate likewise inserted above the reservoir. Here, the air stream is first deflected downward, before it is sucked away upward into the vacuum tank via a perforated plate or the like. During this deflection of the air stream, particles of the coating medium are separated as drops and fall down onto the oblique bottom or into the reservoir. The baffle plate and the perforated plate together are therefore also referred to as a separation means. From here, the coating medium is pumped once again to the application unit in the vacuum chamber. For example, when the coating medium contains oil or oil-containing constituents, an oil mist is located in the air sucked away from the vacuum chamber and reentering the housing above the reservoir and, during deflection by the baffle plate and passage through the perforated plate, cannot be removed or cannot be removed completely. This oil mist may be detrimental to the further coating operation. If the air sucked away from the vacuum chamber is not returned into the vacuum tank, but is led into the working space, the quality of the room air is considerably impaired.